Leading the Roman Army: Soldiers & Emperors, 31 BC–235 AD

By Jonathan Eaton

A historian and archeological scholar examines the complex relationship between Roman emperors and their armies.

For the emperors of Ancient Rome, effective political management of the army was vital to the overall stability of the empire. In Leading the Roman Army, historian Jonathan Mark Eaton examines how emperors endeavored to control the military from the battle of Actium in 31 BC, to the demise of the Severan dynasty in AD 235.

This study draws on the latest evidence from archaeological, epigraphic, literary and numismatic sources on the relationship between the emperor and his soldiers. It demonstrates that the emperor was not only the army’s commander-in-chief, but also their patron and benefactor, even after their discharge from military service.

With forces dispersed along the frontiers of the empire, the emperor needed a strong military hierarchy to impose discipline. He also needed to ensure the loyalty of his officers by building mutually beneficial relationships with them. To this end, the imperial army became a complex network of loyalty ties which protected the emperor from military subversion.

• Language: English
• Publisher: Open Road Integrated Media
• Release date: Jul 30, 2020
• ISBN: 9781473855649

Book preview

LEADING THE

ROMAN ARMY

LEADING THE ROMAN ARMY

Soldiers & Emperors

31

bc

–

ad

235

Jonathan Eaton

img1.jpg

First published in Great Britain in 2020 by

Pen & Sword Military

An imprint of

Pen & Sword Books Ltd

Yorkshire - Philadelphia

Copyright © Jonathan Eaton, 2020

ISBN 978 1 47385 563 2

eISBN 978 1 47385 564 9

Mobi ISBN 978 1 47385 565 6

The right of Jonathan Eaton to be identified as the Author of this work has been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

A CIP catalogue record for this book is available from the British Library.

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Contents

Preface

Introduction

Chapter 1 The Political Influence of the Rome Garrison

Chapter 2 Discipline and Morale

Chapter 3 The Legionary Centurionate

Chapter 4 Commanding the Emperor’s Army

Chapter 5 Political Awareness in the Army

Chapter 6 The Emperor and his Soldiers

Conclusion

Appendix 1 Military Units in Rome

Abbreviations

Editions Used

Bibliography

Notes

Preface

This book has enjoyed a long gestation. Its genesis lies in a childhood fascination with the Roman army, encouraged by family holidays to Hadrian’s Wall and weekend visits to Ribchester. My interest in the command structures of the Roman imperial army was further developed during undergraduate and postgraduate study. In particular, it was encouraged by reading the classic work The Emperor and the Roman Army: 31

BC

–

AD

235.¹ I subsequently had the opportunity to study under the supervision of Professor Brian Campbell at the Queen’s University, Belfast. The research undertaken during this period, supported by funding from the Northern Ireland Department for Employment and Learning, shaped the development of this book.

My passion for the management and operation of the Roman army has been shaped by two extraordinary teachers. Derek Slater introduced me to the rigorous academic study of ancient history based upon a close reading of the classical sources, and believed in me when few others did. Professor Brian Campbell shaped my thinking as a researcher, while advocating a critical approach to the established scholarly literature and encouraging me to situate my own work within its contemporary academic context.

With any piece of writing, it is often the author’s family who pay the highest price in the form of lost time. For this reason, this book is dedicated to Jake, Millie, Heidi and Penny, of whom I am more proud than they will ever know.

Introduction

Many dire events, and particularly those which befell the Romans after the death of Nero, bear witness to this and show plainly that an empire has nothing more fearful to show than a military force given over to untrained and unreasoning impulses.¹

The Empire arose out of a violent usurpation that was the culmination of a series of destructive civil wars waged by rival army commanders. Augustus was the last survivor of a line of generals who used military support to enforce their political will. In securing his pre-eminent position, it was imperative that Augustus prevent his troops from being used against him by ambitious army commanders. In this he was remarkably successful. Over the next two centuries, there would be only two periods of prolonged civil conflict and, in both cases, these were the result of the sudden demise of an established dynasty. Augustus’ army reforms represent his greatest achievement.

During the late Republic, soldiers participated in the political machinations of their commanders, to whom they were bound by personal oaths of allegiance. This process began with Marius’ enlistment of the capite censi, who were reliant on him to provide them with land on their discharge from active service.² The civil wars between Marius and Sulla and later between Caesar and Pompey were symptomatic of the soldiers’ availability as a political weapon. The troops were not silent partners in this relationship and indeed used their military strength to further their own self-interest.³ But personal loyalty also influenced their actions. It is noteworthy that by the end of the Republic, soldiers viewed their allegiance as belonging to individual generals rather than to the res publica. A Pompeian deserter lamented to Julius Caesar: ‘I wish that the immortal gods had made it that I were your soldier rather than Gnaeus Pompey’s, and that I were showing my constancy of courage in your victory rather than his defeat’.⁴

In the aftermath of the assassination of Caesar, soldiers took an active role in influencing the political scene.⁵ His veterans were eager to avenge their fallen leader and looked to Octavian to fulfil this expectation.⁶ Self-interest also motivated their desire to avenge Caesar as they wanted the land rights, which he had granted to them, to be upheld by his successors. For this reason, the soldiers were concerned about the solidarity of the Caesarian faction.⁷ Veterans and centurions, in particular, emphasized the need for reconciliation between Antonius and Octavian.⁸ As Caesar’s adopted son, Octavian could claim the loyalty of the veterans as the successor of their patron.⁹ Yet the soldiers had extremely limited aims and lacked any long-term political vision. Their eagerness to achieve a united front between Antonius and Octavian evaporated once their needs had been met, and they had no qualms about fighting their former comrades when the split between them later became irrevocable. Soldiers’ actions under the late Republic created a clear precedent for troops to intervene politically to further their own aims.

After Actium and the final defeat of Antonius, Octavian oversaw the return of political stability and peace across the empire, as symbolized by the closing of the Gates of Janus, for only the third time in Roman history, in 29 bc.¹⁰ Alongside the necessary demobilization and settlement of Triumviral veterans was a pressing need for the depoliticization of the remaining military formations. Octavian accomplished this by instituting sweeping army reforms that ensured that the privileges and terms of army service would henceforth be under the control of the emperor rather than individual army commanders. Lengths of service, pay and discharge privileges for the various branches of the military were standardized. Soldiers’ salaries and discharge benefits would now be dispensed from the aerarium militare, which was created out of a significant portion of the emperor’s personal fortune and supplemented through the raising of new taxes.¹¹ The temporary armies of the Republic were comprehensively replaced by a permanent imperial institution, which owed its existence and status solely to the emperor.

After the civil wars, Augustus maintained a standing army of twenty-eight legions. Three legions were catastrophically lost with Quinctilius Varus, but more were raised by later emperors. The army consisted of thirty-three legions by the second century ad.¹² Additionally, Augustus began to incorporate native levies into the army as auxiliary units. Auxiliary units eventually made up around half of the total military forces.¹³ A permanent naval fleet was also established, with bases at Misenum and Ravenna. Additional fleets were later created in the provinces.¹⁴ With the exception of the units based in Rome for the emperor’s personal protection, the army was scattered across the frontier regions of the empire, both to deal with the general strategic situation and to displace the threat posed by the concentration of the military in a single area.¹⁵ Regional army groups developed in areas of particular military importance. In the first century, legions were concentrated in Spain, Britain and on the Rhine. By the reign of Marcus Aurelius, the emphasis had shifted to the Danubian provinces, in light of hostile incursions across the river. In the third century, there were increasing military deployments in the Eastern provinces, which reflected the growing status of the Sasanian dynasty and their hostility to Rome.

The purpose of this book is to examine the problems and possible solutions in the management of the Roman army under the Principate. This topic is important because the high value that the emperors placed upon their personal relationships with the soldiers reveals the crucial importance of the management of the army within the workings of the empire as a whole. Although the Augustan army reforms were successful in establishing an effective framework for military service, maintaining the continued allegiance of the soldiers required eternal vigilance by the emperor. We can have sympathy with Domitian’s claim that no one believes in a conspiracy until it is successful.¹⁶ The army always posed a potential threat to the safety and stability of the emperor. I will examine how the command hierarchy and structure of the army were specifically designed to prevent potential rivals from subverting the loyalty of the troops. The overriding factor in ensuring the political allegiance of the soldiers was their relationship with the emperor and this rapport will loom ever present in my study. Given that over twenty years have elapsed since the publication of the fundamental treatment of this theme, a fresh look at the subject is in order.¹⁷ I aim to supplement this work by using archaeological and epigraphic evidence to examine the viewpoint of the soldiers themselves.

Research on the role of soldiers in imperial politics has tended to be constricted by narrow chronological limits, often focussing on the well recorded events of

AD

69, rather than the broad thematic overview that I propose.¹⁸ Anthony Birley has described the political involvement of the imperial army using a narrative format and, in doing so, inadvertently revealed the acute limitations of such an approach, in that it highlights the rare occasions that the system broke down rather than the normal circumstances under which it worked.¹⁹ I have chosen to follow a thematic approach to this problem as the recurring forces at work in both securing and subverting the allegiance of the soldiers can be most clearly understood by deconstructing the various managerial layers within the army. This approach demonstrates the gradual adaptation of the army to changing political and strategic circumstances by analysing, both individually and collectively, the evolution of different methods of managing the troops.

My research is not limited to the relationship between the emperor and the soldiers but rather aims to encompass the power relationships which existed between the different levels of command within the army, notably the centurions, equestrians and senatorial officers. Research on these groups has been limited to a prosopographical approach dealing mainly with their origins, careers and promotion structures. Eric Birley and Brian Dobson, in particular, concentrated on the career structures of centurions and primipilares as a means of understanding how the army was run, in terms of promotions and transfers.²⁰ Work on the equestrian officers has also focussed upon their career patterns and later political success, as exemplified by Devijer’s vast catalogue of their military careers.²¹ The army careers of members of the senatorial order have tended to be examined on a narrow chronological or geographical basis.²² My work aims to transcend these limitations by analysing the political importance of these men and, in particular, their role in managing the army. This approach demands a broad synthesis of much of the existing research on various aspects of the Roman army, which allows me to put forward original insights into the political management of soldiers under the Principate.

A problematic legacy left by Augustus was the permanent deployment of soldiers in and around Rome. A number of different military and paramilitary units were present in Rome throughout this period and their presence at the centre of power necessitated that they be carefully managed. The emperor was forced to delegate the immediate command of these units to carefully chosen individuals, the most important of whom were the Praetorian prefects. Chapter 1 examines the political importance of the various military units in Rome. It will assess the extent to which the Praetorian Guard in particular was able to play a decisive role in imperial politics. It will also look at the role of the Praetorian prefects, their relationships with both the soldiers and the emperor and the criteria by which they were selected for this role. As a key component in his personal security, the emperor was undoubtedly keen to maintain the allegiance of the Rome cohorts and prevent it being subverted by potential rivals. The methods which emperors and usurpers used to win the loyalty of the city units are described in detail.

Augustus ensured that army units outside of Rome were scattered strategically across the empire in order to serve as an effective means of defence. In Chapter 2, I suggest that this led to the fragmentation of the army into different divided elements, which led to some provincial armies developing and expressing their own individual sense of identity. This fragmentation endangered the unity of the army as a whole. Divisions within the army were combated by the spread of customs common to all soldiers across the empire, which, in turn, created a unique military identity separate to and above that of a civilian. The sacramentum, military religious calendar and the transfer of personnel between the provincial armies maintained the unity of the army as a whole. I will explore the various methods used to maintain discipline and morale, which also reinforced the military identity. The breakdown of discipline and a failure in the cohesion of the army could result in a mutiny. The causes and consequences of mutinies under the Principate will be analysed in the context of the potential for small scale disturbance to escalate into direct threats against the stability of the emperor.

Another revolutionary aspect of the new imperial army was the increased importance and enhanced career path open to centurions. Although the increasing status of centurions is evident in Julius Caesar’s commentaries, it was only under the Principate that they were able to reach the senior levels of the imperial administration. Emperors aimed to control their soldiers through the legionary and, to a lesser extent, auxiliary centurions, who functioned as infantry leaders and the primary instigators of military discipline. For the most part these were highly experienced soldiers and provided an invaluable source of military knowledge. Equestrians could receive direct commissions into the centurionate often via the patronage of more senior individuals, if not the emperor himself. Former members of the praetorian cohorts could also be transferred as centurions into the legions. The careers of these men, coupled with the frequent transfers of centurions between provincial armies, ensured that the legionary centurions functioned as a focus of political loyalty towards the emperor and imperial house. In particular, the irregular transfers of groups of centurions during times of political crisis may indicate their use as a stabilizing factor in otherwise rebellious units. This theme is examined in my third chapter.

The sheer size of the empire and the deployment of the imperial army in distinct regional groups forced the emperor to delegate command of his soldiers to his army commanders. Members of the senatorial order usually commanded legions and provincial armies, whereas equestrians could serve as officers in the legions and commanded auxiliary units. These individuals had to build a good working relationship with the soldiers under their command, which gave them the ability to influence their soldiers. This fact forced the emperor to be extremely careful in selecting the men he sent out to command the troops. These commanders and officers had the resources to attempt to seize power for themselves, yet the vast majority remained loyal to their emperor. The attitude of the upper classes towards military service and soldiers in general is valuable for understanding how Augustus was able to exclude members of prestigious senatorial families from important military commands. This is reflected in shifting concepts of the meaning of virtus and the appearance of alternative legitimate avenues for displaying it. My fourth chapter explores the importance of the senatorial and equestrian officers in controlling the troops and the means by which the emperor was able to control their activities.

My final two chapters act in unison to form a coherent whole in analysing the bond between the emperor and his army. As mentioned above, during the late Republic the soldiers began to become politically aware and this continued under Augustus. This awareness created problems in that the formation of military political opinion had to be carefully managed to ensure that they remained loyal to the reigning imperial family. My fifth chapter therefore examines the soldiers’ level of political awareness and the means by which this was controlled. A particular emphasis is placed on the differentiation between formal and informal methods of communication open to the troops, although much depended on levels of literacy within the army. Assessing levels of political awareness for any section of Roman society is difficult, but I will describe three specific cases where the reaction of soldiers to events within the imperial family demonstrates their grasp of political events, namely the deaths of the elder Drusus, Germanicus and Geta.

The central figure in the management of the Roman army was the emperor himself and my final chapter focuses on his personal relationship with his soldiers. His role was predominant in maintaining the political loyalty of the army as a whole and his persona as commilito (or ‘fellow soldier’) was expressed through his conduct towards individual soldiers and behaviour on campaign. I examine the gradual inclusion of members of the imperial family in dynastic propaganda aimed at the army, which is expressed through imagery relating to important individuals on the material culture used by ordinary soldiers. Finally, I discuss a specific image on imperial reliefs to symbolize the relationship between the emperor and his soldiers which has, until now, been overlooked by modern scholars.

In this book I have utilized material from three main fields: epigraphy, numismatics and the surviving literary texts. Each of these sources poses specific pitfalls for the historian. I have relied heavily on five main authors during my research: Pliny the Younger, Tacitus, Suetonius, Cassius Dio and Herodian.²³ These authors were writing from the viewpoint of the upper classes. They did not share the same feelings and opinions as the soldiers; indeed in some cases they despised the army. But all of them had access, through their own rank and status, to information about some, if not all, of the events they described. Pliny, Tacitus and Dio all held consulships and Suetonius served as imperial secretary to Hadrian. Herodian’s career is less clear, but he states that he had witnessed some of the events he describes during his imperial service.²⁴ Nevertheless, as in any era, many of the important issues of state were decided in secret behind closed doors.²⁵ Furthermore, when historians wrote about events outside their own experience, they must have utilized other sources. The reliability of these missing texts cannot be tested and the process of ‘Quellenforschung’ is often highly speculative.

The historian must certainly be alert to possible bias in his sources, but there are also other potential problems lurking in wait for the unwary scholar. The author’s purpose in constructing a particular narrative is often unclear. Was it intended to be a reliable description of events or an exercise in eloquence? In comparing their texts, we must take account of differing intentions and styles. These authors were not writing in the same genre. Pliny the Younger’s works, for example, consist of his published letters and his speech in praise of Trajan. It would be unrealistic to expect to find any criticism of the new regime in his writings. Finally, the political context within which the author worked must be considered. Under the Principate, the writing of history was potentially subversive, as criticism (real or implied) of previous emperors could threaten the prestige of the incumbent princeps. When composing his account of Roman history, the future emperor Claudius wisely chose to include the assassination of Julius Caesar and its immediate aftermath, but exclude the civil wars that followed.²⁶ Some things were best forgotten.

I have also used, to a lesser extent, other classical authors including Velleius Paterculus, whose career I discuss elsewhere.²⁷ The most difficult text to which I have referred is undoubtedly the Historia Augusta. This infuriating mixture of fact, fiction and outright falsehood has been the subject of heated discussion. The current consensus amongst modern scholars is that these imperial biographies were written by a single author towards the end of the fourth century. His motive in writing the work and disguising his identity behind a number of pseudonyms is unknown, but it is clear that the Historia Augusta is a dangerous text for the unwary reader. The life of Severus Alexander, for example, contains a great deal of information about the emperor’s attitude towards his soldiers. However, many of the details are a fraudulent invention and the depiction of Severus Alexander corresponds to the image of an ideal emperor from a fourth-century perspective, rather than the reality of the Severan emperor whose reign was dominated by military ill-discipline.²⁸ For this reason, I have used the text with extreme caution. At no point in this book have I based a supposition solely on evidence from the Historia Augusta, using it instead to supply supplementary material to elucidate an argument further.

Epigraphic material or inscriptions will feature heavily throughout this study. There are a number of factors that must be considered when dealing with inscriptions.²⁹ Epigraphy does not allow us to study the total population, only the individuals who chose to erect inscriptions which were fortunate enough to survive until the present day.³⁰ The ‘epigraphic habit’ reached a peak towards the end of the second century with a quite rapid decline thereafter.³¹ For these reasons, any statistical analysis using epigraphic material can only be of a speculative nature. Like all archaeological material, inscriptions are vulnerable to loss, destruction or reuse. Furthermore, the use of epigraphy varied between provinces. Fortunately, military units and individual soldiers were heavily imbued with the ‘epigraphic habit’ and it is possible to trace the movements of formations and officers through the inscriptions they left behind. However, epigraphy does not represent a source of pure unbiased material. Inscriptions were costly and therefore they were erected for a purpose. Very often they represent the status of the individual concerned, or the status that they wished to be perceived to possess. They do not explain why a particular individual held a specific post and often obscure the correct order in which offices were held. Dating is also problematic, as few inscriptions include a specific consular year. Inscriptions are usually assigned a date on the basis of their style or connection to a known historical event. Historians working with inscriptions usually refer to epigraphic commentaries published in relevant journals and catalogues. This invariably involves placing a degree of trust in the competence and judgement of the published text and commentary. Moreover, care must be taken in separating the actual preserved text from the reconstructions proposed by the epigrapher. There is an inherent danger in viewing history through square brackets.³²

For all its familiarity, there is much about the imperial coinage that we do not know.³³ Any attempt to trace propagandistic themes through numismatic images is plagued by doubts about the validity of the imperial coinage as evidence. It is not clear for whom specific designs were produced. Nor is evidence forthcoming as to how the images on the imperial coinage were received by ordinary people or specific sectors of society. We may assume that the emperor had a level of oversight over the design and production of his coins, but even this point has been debated by modern scholars. Another factor worthy of consideration is the speed and efficiency of coin circulation. How fast would a coin of relevance to the military reach the purse of a Batavian serving at Vindolanda in northern Britain, or an Egyptian auxiliary serving in the Fayum? Slow circulation speeds would inevitably result in coin imagery being of limited political value. These factors are of direct relevance to my study and I have explored them in detail elsewhere.³⁴

On a number of points I suggest parallels from the military history of the modern era. This has enabled me to illustrate particular ideas that may have a universal application. In doing so, I am not suggesting that the Roman army was equivalent to the military forces of the twentieth and twenty-first centuries. On the contrary, I view the Roman army as a unique institution that was remarkably alien from modern concepts of what constitutes a military force. However, I perceive aspects of modern soldierly behaviour which can be applied successfully to the ancient world. In every case, comparative material is used to reinforce an argument, rather than make one.

Throughout this book, I have weighed the ancient evidence judiciously and exercised considerable caution in selecting relevant material. When the sources are problematic, as in passages from the Historia Augusta, or the chronological framework unclear, as in certain inscriptions, I have informed the reader. Despite the challenging legacy of much of the ancient evidence, there is a great deal to be learned from applying it to the problem of the political management of the Roman army. In the words of Syme’s maxim: ‘One uses what one has, and there is work to be done.’³⁵

Chapter 1

The Political Influence of the Rome Garrison